The following information was provided to the Hot Springs Village POA from Steve Frisbee, P.E., Assistant Chief Engineer – Maintenance of Arkansas Department of Transportation.
May 19, 2023
Mill Creek Bridge
An error in the elevation of the retaining wall for the Mill Creek Road Bridge (over the Bypass main lanes) resulted in slopes that were too steep to maintain and did not provide the required safety for drivers. Therefore, the bridge could not be previously opened to traffic and the existing Mill Creek Road was required to remain open, preventing a portion of the new Bypass roadway from being constructed. A change order was approved in September 2022 to construct a new retaining wall to provide the correct safety slopes. The precast wall was designed, fabricated, and constructed, and this bridge work is now completed, allowing the bridge to be opened.
Once the bridge was opened, the contractor was able to obliterate the existing Mill Creek Road to complete construction of the Bypass main lanes. The aggregate base placement is currently being finalized in preparation for final asphalt on the few remaining portions of the project.
Covenant Trail & Quarry Mountain Road Bridges
Upon completion of the main lane bridges over Covenant Trail and Quarry Mountain Road, settlement of the retaining walls on the south end of each bridge occurred. This settlement caused the bridge end expansion joint widths to be reduced, due to rotation of the bridge backwalls.
This settlement was not due to improper work by the contractor, rather was due to subsurface ground settlement below the embankment fill. The varying geologic formations in the Hot Springs area, with varying layers of rock, such as sandstone, shale, weathered shale, novaculite, etc. create challenges in highway design and construction. The settlement was investigated by ARDOT Materials Division and a 3rd party geotechnical engineering consultant to identify the issues and provide a solution.
A Change Order was recently approved to perform subsurface compaction grouting below the bridge end retaining walls to densify and stabilize the embankment, and to reconstruct the bridge end backwalls to provide the proper movement and expansion of the bridge.
The geotechnical contractor (Keller) is scheduled to mobilize the week after next, then begin compaction grouting work on June 5th week. The bridge backwall remediation will follow. It is estimated that it will take approximately 12 weeks total to complete the work.
Keller’s website provides a great explanation of compaction grouting: https://www.keller.com/expertise/techniques/compaction-grouting
ARDOT and our Contractor, McGeorge are continuing to work together to expedite the work and looking forward to opening this beautiful and important bypass as soon as possible. ………..Steve Frisbee, P.E., Assistant Chief Engineer – Maintenance of Arkansas Department of Transportation.